Questions tagged [digital-signature]

A digital signature (not to be confused with a digital certificate) is an electronic signature that is used to authenticate the identity of a message sender or document signer, and usually to ensure that the original message/document content is unchanged (document integrity).

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2answers
473 views

Are there any meta-formats for crypto?

Are there are any (properly specified) meta-formats / schema formats for describing cryptographic message structures? I'm looking for a way to describe the format (where some channels might want ...
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How does an attack on a digital signature work?

In our IT Security class we have been told that you need CA's to prevent attacks on a digital signature. Sadly, our docent didn't elaborate how such attack would be performed - I can only guess that ...
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Authencity of information displayed on an untrusted device

Suppose I have a (bluetooth/usb) device which needs to displays information on an external pc/phone. Is there a simple and effective method to garantuee that the information displayed hasn't been ...
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3answers
839 views

Most widespread use of PGP after 20 years

Phil Zimmerman released PGP (Pretty Good Privacy) on June 5, 1991. As we examine the legacy of that far-sighted and brave act 20 years later, what are the most widespread and helpful uses of PGP ...
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3answers
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How do I produce a CA signed public key?

I have a need to have somebody else encrypt secret data with my public key that I can then decrypt with my private key. I have produced an RSA private/public key pair with OpenSSL gave them the public ...
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4answers
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What good, standard digital signature / timestamp verification clients are widely or easily deployed?

I'm looking for a good way to publish data along with a digital signature (and ideally a timestamp) which is as easy as possible to verify via software run locally on public data. For example, ...
9
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1answer
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The security of sending emails with SPF/DKIM, but not signed

We're using an email sending service (fairly known) to send our emails. We made DNS changes so that emails going through them would pass SPF and DKIM. A few days ago we noticed that they allow any ...
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2answers
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Why does Microsoft use a digital signature catalog instead of a signature in the executable?

I own a code signing certificate, so I can add digital signatures on files that contain executable code. Microsoft seems to use a "new" way and provides most digital signatures not in the file itself ...
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7answers
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Proving running code on a website is unchanged

Can it be proved to the user that the running code behind a website with security related code is the same as published? I'm currently looking at a few new project ideas and one involves secure ...
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499 views

Electronic identity and digital signatures - why they are different?

It seems (to me at least) that is is generally accepted that "electronic identity" and "digital signatures" are a different thing. For example, in the Estonian ID card there are two certificates - one ...
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Why are apps signed?

From the Android website: Android requires that all apps be digitally signed with a certificate before they can be installed. The signature ensures that only the original developer can publish ...
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2answers
547 views

Is a mail secure if it's PGP-encrypted, but unsigned when sent with DKIM?

I run my own mail server and would like to use different addresses on the same domain. If I were to sign mails from those addresses, I'd have to generate new PGP keys for each and every one of them. ...
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Can a zero knowledge proof of voting be made using a trusted auth server (without client side crypto)?

Questions: Can one implement a secure voting system having all the features described below? e.g. without disclosing any individual's vote to the government server (or the third party), preserving ...
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What is the difference between the “sig” files and the checksum files, such as on the PuTTY download page?

This is about the functional differences between sig files and checksum files and how they can be used by a user downloading some software. For example, on the PuTTY download page both sig files and ...
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2answers
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How do systems protect against a stolen code-signing certificate after the certificate expires?

Imagine this scenario: 1st December 2014 - a certificate is stolen and used to sign malware with 2014-12-01 timestamp. 15th December 2014 - the certificate is revoked. Malware will be prevented from ...
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2answers
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Enforce Code/Script Signing

I have both a couple of X.509 Code Signing certificates and a GPG keypair that I can use to sign against code I run on my VPS. Every now and again I write code for iOS, OS X and Windows and always ...
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1answer
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How do I verify a GPG signature attached for a cleartext email using the gpg command line?

I received an email in cleartext from someone with a signature.asc attached. Looking at the raw source for the email, it was sent with Apple Mail + GPGMail. Reading the message in Thunderbird + ...
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1answer
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Parsing a PKCS7 detached signature hash

I'm trying to manually verify signatures of Apple iOS Passbook files, which are PKCS #7 detached signatures of the RSA key of the Apple developer who created the file. Which means there's a file "...
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3answers
970 views

Is piping a `ssh-agent` signed message as a password secure?

There's an encrypted filesystem on a server I ssh into using public key authentication. Since a forwarded ssh-agent can deterministically sign a message (see also the ssh-agent protocol section 2.6.2),...
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2answers
196 views

Verifying cryptographically signed files when the key has been revoked

This is mostly a question out of idle curiousity. If I use my private key to sign a file today, forming a signature, and distribute that signature with the document to someone they can then use my ...
8
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1answer
170 views

Subresource Integrity versus signing

The draft spec for subresource integrity is straightforward: This document specifies such a validation scheme, extending two HTML elements with an integrity attribute that contains a ...
8
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1answer
5k views

ADFS: Verify requests from relying party

In ADFS, serveral certificates are used. This is explained (very clearly) on this page: http://blogs.technet.com/b/adfs/archive/2007/07/23/adfs-certificates-ssl-token-signing-and-client-authentication-...
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Why do the roles of public/private keys reverse when talking about public key encryption and digital signatures?

With public key encryption you encrypt using a public key. But when creating digital signatures you sign by encrypting a hash using a private key. I understand the principles of these two uses of ...
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4answers
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when people say a file has a checked md5 hash, what exactly does that mean?

ok I was just reading this site: http://www.zdnet.com/blog/bott/stay-safe-online-5-secrets-every-pc-and-mac-owner-should-know/3542?pg=4&tag=mantle_skin;content and thought of something I always ...
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Why can I sign but not encrypt?

-edit- After following a chain of links from this question I see this is similar/duplicate of Why should one not use the same asymmetric key for encryption as they do for signing? but this question ...
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3answers
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Digital Signature and Verification?

AFAIK , When Alice wants to write a message to Bob -- she uses Bob's public key and encrypt the message - and then Bob - using his private key - use to decrypt it. So public key is used to decrypt ...
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2answers
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Is it safe to store APK signing passwords in private git repository?

I develop android game using cocos2d-x. For android release, it contain this fields in proj.android/gradle.properties: # uncomment it and fill in sign information for release mode #RELEASE_STORE_FILE=...
7
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1answer
718 views

How to create email that will fool DKIM verifier?

Sammy the sender is sending email to Rita the recipient. I know Sammy will apply a DKIM signature to the email and Rita is going to check the DKIM signature with a DKIM validator. I am a malicious ...
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1answer
7k views

Public key length

I was wondering if there was (and I hope there is) a standard for public key size for ECDH (Elliptic Curve Diffie-Hellman) and ECDSA (Elliptic Curve Digital Signature Algorithm) for every curve type ...
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3answers
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Why does my rundll32.exe not have a verified signature?

In the task manager, I saw an instance of rundll32.exe running, no big deal. Just for fun, I wanted to upload the source file to VirusTotal. Where I noticed, the rundll32.exe file does not have the ...
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1answer
593 views

OpenPGP Encryption / Decryption Process Using GnuPG

I want to know if my method of encryption can ensure the security of my data if my database was hacked as well as the authenticity of the data I am decrypting. I am using GnuPG's implementation of the ...
7
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1answer
796 views

Why are PGP signatures not more widely used as an authentication method?

Example: Bob generates a key pair for this example. Bob registers at example dot com where he provides his public key. When Bob will try to log in, example dot com will ask him to sign a random ...
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3answers
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End to end security for REST services, any emerging standards?

I work with integration in the healthcare sector, where end-to-end security is important. We integrate with numerous SOAP services, and use the WS-security features to encrypt and sign requests and ...
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1answer
512 views

How can I sign an rpm package using a smart card?

I have a smart card (not OpenPGP card), and I am preparing to sign an rpm using this card. After signing, I will get two files: my.rpm.sig, and my_id.cer. How can I sign my rpm using these extra ...
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1answer
1k views

Reading older mails signed with a certificate that has meanwhile expired

A few years ago I have used S/MIME certs to sign (and encrypt) my mails. The reason for which I stopped signing was the following: My (class 2) cert was issued on Jan. 1st 2008 (just a sample). It ...
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1answer
1k views

How do certificates work in terms of encryption, hashing, and signing?

I think I might understand this stuff, but I want to be sure I've got the details correct. There is a lot of information out there on the high-level implementation of certificates, as well as the ...
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3answers
2k views

Is there a way to accept signed requests without storing client's password in plaintext?

We are developing REST Web service. We will give Identifier and Secret string to each of our REST clients. When doing requests, clients will authenticate themselves using HMAC algorithm (they will ...
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3answers
1k views

How can I prove that I wrote a certain blog post?

I would like to be able to prove that I wrote the article that resides at a given URL on someone else's blog. Is there a way that I can do this with public key cryptography? I know a bit about the ...
6
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3answers
642 views

DHE exchange and client authentication

If a server has a known public key and a Diffie-Helman exchange is performed and signed by that key, is there any benefit to authenticating the client before establishing a secure channel instead of ...
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3answers
6k views

Confidentiality with digital signatures

Recently I have been working with digital signatures. Some common reasons for applying a digital signature in communication are authenticity, integrity and non-repudiation. Do digital signatures ...
6
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1answer
1k views

Is Ed25519 still secure, despite the fault attack published in 2017?

I heard that Ed25519 is a new digital signature. It has smaller public key size and generates a public key more quickly. I read an article about Ed25519 titled Practical fault attack against the ...
6
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1answer
6k views

Can Fiddler decrypt HTTPS traffic when using elliptic curves + client cert authetication?

Case 1 involves TLS + client certificate authentication with both client and server using secp384 based EC certificates. In this case, when monitoring traffic via fiddler, the tunneling/handshaking as ...
6
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2answers
785 views

Is it safe to use a Windows executable with expired SHA256 certificate but valid SHA1 certificate?

Microsoft's Media Creation Tool to create Windows 10 installation media has a SHA1 digital signature and a SHA256 digital signature (shown via file properties). However, the certificate for SHA256 ...
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3answers
1k views

Why would I use MAC over digital signature?

As far as I've read, there is no benefit of a MAC over a digital signature - except the fact that it is faster to generate and process. Is this true? Digital signatures (asymmetric encryption) seem ...
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1answer
1k views

Is there an algorithm to generate digitally signed URL links?

Scenario: Alice prepares an URL link to Bob's web service (e.g., http://www.bob.com/sensitiveData/123?login=mallory). Alice gives the URL link to Mallory. Mallory follows the link to trigger an ...
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2answers
5k views

Dealing with expired or revoked signing certificates with Infopath documents

Suppose I have an Infopath form that is digitally signed today by a valid, and active user. When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...
6
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1answer
2k views

multiple authenticode signatures

Is it possible to have multiple Authenticode signatures in an executable? The Digital Signatures tab suggests you can, so I was wondering if, for example, you can sign an executable with Verisign's ...
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1answer
3k views

Signing session cookies

The Play Framework for Scala has support for signed session cookies. In the application configuration file is an "application secret" that is set as a secure random number when the application source ...
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2answers
3k views

What are the real-time applications of long term digital signature with timestamp

I want to know the real time applications that uses digital signatures with timestamps. Specially I am interested to know the applications where we can trust an old signed document which is now ...
6
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1answer
431 views

How to Get and Set Digital Signatures with FDA 21 CFR Part 11 Standards

How do I get and set digital signatures with the 21 CFR part 11 standards as defined by the Food&Drug Administration of the USA?

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